This invention relates to composite structures that retain their structural integrity despite exposure to the wear erosive and/or corrosive effects of sudden high pressures, high-pressure friction forces and high temperatures typically associated with their use, particularly within the interior of the structure. The present invention may be especially adapted for use in gun barrels, piston cylinders, pipes or other composite structures where the retention of structural integrity despite exposure to such brisant forces is an integral component of their ordinary application.
Gun barrels for example, are structures that have typically been constructed of metallic materials that are incorporated to accommodate a projectile or bullet that may then be propelled out of the barrel as a result of an exploding cartridge in the breech end of the structure. During this firing process, brisant forces, including high pressure and elevated temperatures, resulting from the hot gases released from the cartridge and friction and distortion energy created between the bullet and internal circumference of the barrel, are suddenly exerted on the barrel as the bullet travels along and out of the barrel. Gun barrels that are consistently exposed to these brisant forces, such as machine gun barrels that expend hundreds of rounds per minute, are more prone to losing their original structural integrity as the metallic material begins to expand and warp as a result of elevated temperatures exerted on the barrel or the barrel becomes clogged with an accumulation of lead and/or copper that breaks away from projectiles as they exit the barrel. This is of particular concern in gun barrels where the diameter of the barrel expands such that the internal circumference of the barrel no longer holds enough compression to effectively launch a projectile, or the projectile falls short of the desired distance, rendering the gun ineffective. Alternatively, gun barrels have also been known to explode and cause physical injury or death to their operators as a result of deformed, warped or clogged barrels. These concerns have become increasingly significant as advancements have been made in ballistics which have produced higher powered propellants, higher muzzle velocity, higher rates of fire and so forth, making the probability of these phenomena more likely.
In response to these phenomena, many attempts have been made to produce barrels made of tough, high strength materials that can accommodate such advancements and are capable of withstanding the detrimental effects of sudden high pressures and temperatures normally associated in ordinance use. Despite concerted efforts, many of these developments have yet to prove effective in their application because materials that yield high strength characteristics may conversely have very low toughness properties making the barrel brittle and more susceptible to breaking or exploding, while materials that exhibit high toughness properties may conversely exhibit low hardness making them more susceptible to erosion.